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SCDSET.MEM -- For Version 3 of SCDSET
Jan 1978
COPYRIGHT (C) 1977,1978 BY
DIGITAL EQUIPMENT CORPORATION, MAYNARD, MASS.
THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY BE USED AND COPIED
ONLY IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE AND WITH THE
INCLUSION OF THE ABOVE COPYRIGHT NOTICE. THIS SOFTWARE OR ANY OTHER
COPIES THEREOF MAY NOT BE PROVIDED OR OTHERWISE MADE AVAILABLE TO ANY
OTHER PERSON. NO TITLE TO AND OWNERSHIP OF THE SOFTWARE IS HEREBY
TRANSFERRED.
THE INFORMATION IN THIS SOFTWARE IS SUBJECT TO CHANGE WITHOUT NOTICE
AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT
CORPORATION.
DIGITAL ASSUMES NO RESPONSIBILITY FOR THE USE OR RELIABILITY OF ITS
SOFTWARE ON EQUIPMENT WHICH IS NOT SUPPLIED BY DIGITAL.
SCDSET.MEM Page 2
SCDSET: A Scheduler Parameter Setting Program
for use by the System Administrator
1.0 OVERVIEW
1.1 Purpose
The purpose of this program is to allow the System Administrator to
easily use the SCHED. Monitor call as implemented in the DECsystem-10
6.02 monitor. (This monitor call allows a privileged user to set
system usage quotas as well as adjust scheduler parameters.) The
program is written so that the System Administrator can exercise the
monitor call easily without having to know how it was implemented. In
addition SCDSET:
1. Allows the System Administrator to create/modify a SCDMAP.SYS
file (which maps Scheduler Types to Scheduler Classes).
2. Allows the System Administrator to move any SCDMAP.SYS file
to the SYS area (so that the new map is being used by new
LOGIN's).
3. Allows the System Administrator to automatically update the
class of all logged in jobs.
1.2 Relation to Other Programs
This Version of SCDSET is valuable only for a site running the
scheduler LIR and Version 6.03 or 6.04 and later versions of the
DECsystem-10 monitor. Several of SCDSET's auxiliary functions require
Version 4 of ACCT.SYS. This requires new versions of three other
systems/programs that access ACCT.SYS: LOGIN (Version 56A or later),
REACT (Version 31 or later) and SPRINT-10 (Version 2A(1056) or later).
1.3 DESIGN Goals
1. Write a simple, easy to use program that has enough hooks to
do anything that the SCHED. monitor call can do.
2. Implement it in some higher level language so that
modification of SCDSET by the System Administrator is easier.
(FORTRAN-10 was chosen arbitrarily.)
SCDSET.MEM Page 3
1.4 Bibliography
See the System Administrator's Guide to the 6.02 Scheduler, and the
appropriate documentation of REACT, LOGIN, and SPRINT-10.
2.0 PRIVILEGES REQUIRED
For manipulating a SCDMAP.SYS file, no privileges are required (except
as needed to move that file to the SYS area).
For exercising the SCHED. monitor call, all privileges are required.
The user must be logged in as [1,2], or the program must be JACCT
priviledges. These are the restrictions of the monitor call.
The READ/SET functions of SCDSET assume the user is [1,2] and will
otherwise fail.
3.0 CAUTIONS
The System Administrator is strongly advised to run SCDSET in a high
priority queue (HPQ). This will assure that his/her work is
unaffected by system quota's and system load.
HPQ is not required when creating/modifying a SCDMAP.SYS file, and is
in fact discouraged because it has a detrimental effect upon system
performance.
4.0 FUNCTIONS
The program SCDSET prompts the user with a message asking for a
command (and optionally a parameter selecting a particular function
associated with the command). The user types in the name of the
command and if necessary the optional parameter.
Commands:
1. HELP - Types out help text.
2. EXIT - Returns to the monitor
SCDSET.MEM Page 4
4.1 Update Jobs
The UPDATE JOBS command calls the FIXJOB routine. This routine first
reminds the System Administrator that a new SCDMAP.SYS file should be
on the SYS area by asking him if he wishes to move one there. If the
System Administrator does want to move a map to the SYS area, FIXJOB
calls the MOVMAP routine to do that work. FIXJOB then runs through
each logged in job, gets that job's PPN, determines whether or not to
use the batch half of the SCDMAP.SYS currently on SYS, looks in
ACCT.SYS for the Scheduler Type of that user, and executes the SCHED.
monitor call to put that job in the right Scheduler Class. It prints
out an error message for each logged in job it could not find in
ACCT.SYS or for which the SCHED. monitor call failed. The FIXJOB
routine does not execute the SCHED. monitor call for [2,5] jobs, or
for its own job.
4.2 EDIT
The EDIT Command calls the MAKMAP subroutine. This routine will
create/modify a SCDMAP.SYS file. There are eight (8) subcommands
available:
1. HELP - Type out a help text.
2. EXIT - Exit to top level.
3. READ - Read in a SCDMAP.SYS file for modification.
4. WRITE - Write out a SCDMAP.SYS file to any device or area.
5. RANGE - Change any range of Scheduler Types to scheduler
Classes in the map.
6. ONE CLASS - Change one Scheduler Type to a Scheduler Class in
the map.
7. TYPE - Type out any range of Scheduler Types.
8. COPY/SET - The COPY command calls the MOVMAP routine. This
function merely copies a file from any area or device to the
SYS area. PIP should be able to do this work, but this
routine is provided for the convenience of the System
Administrator.
SCDSET.MEM Page 5
4.3 READ/SET Functions
The user types READ or SET on the keyboard followed by a comma and a
parameter form the following list. These functions directly execute
the SCHED. monitor call.
1. MS INTERVAL - This function reads or sets the Micro
Scheduling Interval. (The interval at which the scheduler
changes which class it will select from first during the next
scheduling interval). The interval is in jiffies.
2. PRIMARY PERCENTAGES - System usage percentage for a particlar
job class. The sum of all primary percentages may be fixed,
in which case a job will only be chosen to run when its class
has highest priority.
3. TIME BASE - Base run quanta for either run queue. This
measurement is in milliseconds. (Internally the Scheduler
stores this value in local jiffies, so it may not be possible
to adjust the time slice by a few milliseconds.)
4. JOB CLASS - This function reads or sets the Scheduler Class
of all logged in jobs.
5. PROTOT - This function reads or sets the Scheduler constant
called PROTOT. It is one of the three constants used when
calculating the Minimum Core Usage quota. The measurement is
in microseconds.
6. RUNTIME BY CLASS - This function reads the amount of runtime
used by each class since the last time that a class quota was
changed. The measurement is in jiffies. The routine also
prints out the percentage of runtime each class has used.
7. PROT - This function reads or sets the value of the Scheduler
constant called PROT. It is one of the constants used in
calculating the Minimum Core Usage quota. The measurement is
in microseconds.
8. DEFAULT CLASS - This is the default class that new jobs are
placed into when they first login. This class is used until
it is changed by LOGIN after LOGIN has read the specified job
class from SCDMAP.SYS.
SCDSET.MEM Page 6
9. PROT1 - The in-core timeslice used after a job has been
either expired its initial in-core protect time. This
control the rate at which I/O bound jobs circulate around the
run queues.
10. PROTM - PROTM is the maximum in-core protect time that will
be assigned to a job. It specifies an upper bound for very
large jobs.
11. TIME MULTIPLIER - Used to assign a larger quantum runtime for
large jobs. The quantum runtime is computed by adding the
TIME BASE to the TIME MULTIPLIER multiplied by the job size.
The result is compared with a run quantum maximum, and the
smaller of the computed value or maximum is used.
12. TIME MAXIMUM - The maximum quantum runtime that is used, as
described above.
13. SECONDARY ALLOCATION - The secondary allocation for a
scheduler class. When no runnable job can be found in the
primary class that has been selected to be in proportion to
their secondary allocation.
14. RESPONSE FAIRNESS - The response fairness factor control how
often jobs will be run according to their order in the "just
swapped in list", in preference to the allocations specified
by the job classes.
15. AVG SWAP TIME - This parameter is an estimate of the average
swap time for a typical job in the system. it controls the
rate at which the swapper changes from one class to the next
in chosing jobs to swap in.
16. BB CLASS - Selects which class is background batch, a class
that is run whenever the system is otherwise idle.
17. BB SWAP TIME - Estimate of the time required to swap a
background batch job. This is used by the scheduler to
decide when the system has been idle long enough to permit
swapping in a background batch job.
18. SCHEDULER FAIRNESS - This parameter determines how oten PQ2
jobs will be scheduled ahead of PQ1 jobs. This parameter
allows compute bound jobs to run (albeit slowly) even when
there is an abundance of interactive jobs.
SCDSET.MEM Page 7
19. SWAPPER FAIRNESS - This parameter determines how often PQ2
jobs are swapped in before PQ1 jobs. It has the same effect
on the swapper as the scheduler fairness factor has on the
scheduler.
20. INCORE FAIRNESS FACTOR - The parameter control how often an
out of core job is scheduled before for swapping before a job
that is already in core. This allows jobs to be swapped in
when many jobs that are already incore are doing GETSEG's.
21. CORE SCHEDULING INTERVAL - This controls how quickly the
system will assume that there is sufficient core for all jobs
and stop accounting for incore protect time and using it to
requeue jobs. This happens on systems with a large amount of
core memory or when the system has very few users.
5.0 COMPILING INSTRUCTIONS
There are two modules necessary to compile and run SCDSET. They are
SCDSET.FOR and SCDEXE.MAC. SCDSET contains the top level command
loop, the error message routine, all the functions, and routines to do
all the work required by the System Administrator. SCDEXE contains
the few MACRO routines necessary to execute the SCHED. monitor call
and to gather environmental information not available from FORTRAN.
Version four (4) of the FORTRAN-10 compiler was used to compile this
code. Any MACRO should be able to handle the SCDEXE module. A simple
"LOAD SCDEXE, SCDSET" and then a save should be sufficient to make a
copy of the SCDSET program.
6.0 THE SCDMAP.SYS FILE
The SCDMAP.SYS file should always be on the SYS area when your system
is running a 6.02 monitor and a LOGIN that sets 6.02 quotas. LOGIN
will complain if there is no SCDMAP.SYS file on SYS.
The file contains 1024 (decimal) nine bit entries (256 decimal words).
The first 512 entries constitute the map for timeshare users, the
second 512 entries constitute the map for batch users. Each entry
contains a number between zero and thirty-one inclusive (0-31)
specifying a Scheduler Class. There is an entry for each of the 512
Scheduler Types for both timeshare and batch. Thus at login time,
LOGIN looks in ACCT.SYS for the Scheduler Type of the PPN and then
looks in SCDMAP.SYS for the current Scheduler Class for that Scheduler
Type and job type (timeshare or batch). For sites that do not wish to
differentiate between timeshare and batch, the second half of the map
should be identical to the first half.
SCDSET.MEM Page 8
The format of the SCDMAP.SYS file is as follows:
bits
0-8 9-17 18-26 27-35
*****************************************
word 0 * * n0 * n1 * n2 *
n3 * * *
*****************************************
word 1 * * n4 * n5 * n6 *
n7 * * *
*****************************************
word 2 * * n8 * n9 * n10 *
n11 * * *
*****************************************
/ /
/ /
*****************************************
word 127 * n508 * n509 * n510 * n511 *
*****************************************
word 128 * m0 * m1 * m2 * m3 *
*****************************************
word 129 * m4 * m5 * m6 * m7 *
*****************************************
word 130 * m8 * m9 * m10 * m11 *
*****************************************
/ /
/ /
*****************************************
word 255 * m508 * m509 * m510 * m511 *
*****************************************
***where nXXX is the location of the Scheduler Class for timeshare
users of Scheduler Type XXX (as stored in ACCT.SYS), and mXXX is the
location of the Scheduler Class for batch users of Type XXX.
7.0 WARNINGS
It is very easy when using SCDSET to halt all productive work being
done on the system. Misunderstanings of how the scheduler works or
typing errors when using SCDSET could drastically affect system
performance. The System Administrator is strongly urged to experiment
with this program and the 6.02 scheduler during non-production
timesharing, until he/she becomes familiar with both SCDSET and the
scheduler.
[End of SCDSET.MEM]